1. Field of the Invention
The present invention relates to an information processing apparatus and a method therefor, and in particular to an information processing apparatus for using a 3D model (computer aided geometry model in 3D) generated by using 3D-CAD, and a method therefor.
2. Related Background Art
Conventionally, a CAD apparatus (especially, a 3D-CAD apparatus) is employed to design objects (hereinafter simply referred to as parts) having a three-dimensional shape, such as parts for goods or products. Further, based on this design, metal molds for manufacturing parts are generated.
Before using the design information prepared by the CAD apparatus, attribution information, such as dimensions, dimensional tolerances, geometric tolerances, annotations and symbols, are entered for a 3D model (3D geometry).
In order to enter this attribution information for the 3D model, planes, ridge lines, center lines and vertexes of the 3D model are selected. For example, attribution information shown in FIG. 26 is entered for a 3D model shown in FIG. 24 (the front view, the plan view and the side view of this 3D model are shown in FIG. 25). The attribution information includes:                distances (lengths, widths and thicknesses), angles, hole diameters, radii, chamfering dimensions, and dimensional tolerances accompanied by dimensions;        geometric tolerances and dimensional tolerances to be added to planes and ridge lines, without dimensions being entered;        annotations to be transmitted or instructed for machining or manufacturing parts, units and products; and        symbols that are determined in advance as a premise for representing, for example, surface roughness.        
For adding attribution information to a 3D model, roughly two methods, as follow, are employed.    (1) Method for adding dimensions, dimensional tolerances, geometric tolerances, annotations and symbols            Dimension lines and projection lines are required for the entry of dimensions and dimensional tolerances.        Leader lines are required for the entry of geometric tolerances, annotations and symbols.            (2) Method for adding dimensional tolerances, geometric tolerances, annotations and symbols without dimensions being provided.            Dimension lines and projection lines are not required.        Leader lines are required for the entry of dimensional tolerances, geometric tolerances, annotations and symbols.        
Further, a metal mold is produced by using a 3D model. In this case, an examination must be performed to determine whether a metal mold and a product for which the metal mold is used are obtained as designed.
The following problem has arisen with the conventional method for adding attribution information to the 3D model.
In case (1) described above, a dimension and a dimensional tolerance, and a dimension line and a projection line used to enter the dimension and the dimensional tolerance, become complicated, and it is difficult to see the geometry of a 3D model and the attribution information.
If, as is shown in FIG. 24, the 3D model has a comparatively simple shape and there are only several tens of attribution information sets, they can somehow be identified. However, since several hundreds or thousands, as needed, of attribution information sets are provided for a 3D model having a complicated or large shape, the reading of attribution information is extremely difficult because “attribution information sets are overlapped”, “attribution information is overlapped with the dimension line, the projection line or the leader line”, or “the position of the dimension line, the projection line or the leader line is not easily apprehended”. It is rather difficult to see even the step-shaped corner shown in FIG. 26.
In the above case, since it is difficult for an operator to see attribution information that is input, the operator can not confirm the contents of input information, i.e., the input of attribution information becomes difficult.
In addition, the reading of associated attribution information is also extremely difficult. Further, since the space occupied by attribution information is increased for a 3D model, the geometry of the 3D model and the attribution information can not be seen at the same time on a display screen having a limited size.
Furthermore, for the attribution information (e.g., the depth of a 12±0.1 counter bore in FIG. 24) that is to be designated in the cross-sectional view, for example, the location whereat the attribution information is provided for the 3D model does not appear and is hard to be understood.
In case (2), since the leader line is employed while the dimension line and the projection line are not required, as in case (1), the leader lines are complicated and it is difficult to see the geometry of the 3D model and the attribution information. Further, since several hundreds to several thousands, as needed, of attribution information sets are provided for a 3D model having a complicated or large shape, the reading of attribution information is extremely difficult.
In addition, the measurement of dimensions is required in the process for examining a manufactured metal mold and a product obtained using the metal mold. Therefore, the operation using the measurement function for 3D geometry is required in order to read the dimensional values.
In this case, a portion that is used as a reference dimension must be selected to read a desired plane or ridge line. In order to read the dimensions of a plurality of portions, many operations and a long processing time are required. Further, erroneous readings due to mistakes can not be avoided. Furthermore, an extremely large amount of labor is required to read the dimensions of all the portions.
Originally, a 3D model and attribution information are data for the machining or manufacture of parts, units and products, and must be transmitted efficiently and accurately by a data input operator, i.e., a designer, to a recipient operator, i.e., a machining, production or inspection engineer, so that the data can be easily understood. The conventional technique does not satisfy these requests, and is not industrially effective.
It is, therefore, one object of the present invention to add attribution information to 3D data generated by a CAD apparatus, so that the information can be transmitted efficiently and accurately and can therefore be easily understood. It is another object of the invention to add attributions to data to improve the operation.
It is an additional object of the invention to efficiently employ an attribution that is added.
It is a further objective of the invention to efficiently produce parts by utilizing data created by a CAD apparatus.
It is a still further object of the present invention to efficiently perform an inspection process by using data created by a CAD apparatus.